Somatic embryogenesis in the Diyarbakir watermelon (Citrullus lanatus cv. sürme)

This research, aimed to develop a regeneration protocol via somatic embryogenesis in the Diyarbakir watermelon (Citrullus lanatus cv. Sürme). Two different experiments were conducted: Experiment I and Experiment II. In the Experiment II, MS (Murashige and Skoog 1962) was used as a medium and was supplemented with a combination and concentration of TDZ ( 0.1, 0.25, 0.5 mg/l), NAA (0.5, 1.0, 1.5 mg/l), and 2.4-D (0.5, 0.75, 1.0 mg/l). Cotyledon segments from 20-days-old seedlings derived from mature seed of genotype Sürme were used as an explant. In Experiment II a medium of MS was supplemented with a combination of BAP (1.0, 2.0, 3.0 mg/l), TDZ (0.1, 0.25, 0.5 mg/l), NAA (0.05, 0.1, 0.5 mg/l), and 2,4-D (0.1, 0.5, 1.0 mg/l). Cotyledons, hypocotyls, and cotyledon nodes from 5-days-old seedlings derived from mature seed of Surme were used as an explant. In the Experiment I, supplementing with combination and concetration of TDZ + NAA, the rate of callus formation was 100%. Although the calli were then transformed embryogenic calli, in rate of 100%, except of calli, culturing in MS medium contained single NAA concentrations. Moreover, quite high amount of calli formed from each explant and an average calli weight were determined between 820.1 and 4184.25 mg. In the Experiment II, callus formation rate ranged from 89% and 100% for the combination and concentration of BAP + 2,4-D, and ranged from 61.27% and 100% for the combination and concentration of BAP + NAA. In regard to embryogenic calli, the rate ranged from 75% to 100% for the combination and concentration of BAP + NAA, while it ranged from 0.62% to 86.21% for the combination and concentration of BAP + 2,4-D. The most somatic embryo formation was observed at the combination and concentration of BAP + NAA. The highest average number of somatic embryo (23.2) was determined in MS medium contained 3 mg/l BAP + 0.5 mg/l NAA. In regard to explant types, the highest average number of somatic embryos for cotyledon, hypocotyl, and cotyledon node were 62.6 (3 mg/l BAP + 0.5 mg/l NAA), 46.9 (1 mg/l BAP + 0.5 mg/l NAA), and 11.3 (2 mg/l BAP + 0.05 mg/l NAA). The rate of germination of somatic embryos, in regard to different maturation and germination mediums (MS); IAA (1 mg/l), control (PGR-free), and Kin (1 mg/l) were 52.7%, 35.5%, and 31.8%, respectively. The highest rate of plantlets derived from germinated embryos were 95.5%, 80.2%, 77.3%, respectively for the control, IAA, and Kin contained MS medium. Regenerated plantlets via somatic embryogenesis in the Diyarbakir watermelon (Citrullus lanatus cv. Sürme), undergoing acclimatization were successfully transplanted to the field. In addition, secondary somatic embryogenesis and organogenesis also were determined.